Bellows sealed firing pin

ABSTRACT

A firing pin bolt assembly includes a tubular bellows having one end sealed to and about the penetrator end and its other end sealed to the bolt about the firing pin passageway.

United States Patent lnventors Eugene Ashley Burlington; Douglas Pray Tasie, St. George, Vt. 843,728 July'22, 1969 May 4, 1971 General Electric Company Appl. No. Filed Patented Assignee BELLOWS SEALED FIRING PIN 12 Claims, 2 Drawing Figs.

US. Cl 89/26 Int. Cl F4lf 11/00 Field of Search..; 42/16;

IMPACT FORCE lli/ll [56} References Cited UNITED STATES PATENTS 2,480,100 8/1949 Weiss et a1 39/26 3,] 14,290 12/1963 Harvey et al 89/26 3,166,864 1/1965 Scanlon, Jr. 89/26 Primary ExaminerBenjamin A. Borehelt Assistant Examiner-C. T. Jordan Attorneys-Bailin L. Kuch, Irving M. Freedman, Harry C.

Burgess, Frank L. Neuhauser, Oscar B. Waddell and Joseph B. Forman ABSTRACT: A firing pin bolt assembly includes a tubular bellows having one end sealed to and about the penetrator end 7 and its other end sealed to the bolt about the firing pin passageway.

Patented May 4, 1971 l P CT 34 P 46 as a I2 FIG! IIIIIIIIII III THEIR ATTORNEY.

INVENTORSI EUGENE ASHLEY, DOUGLAS P. TASSIE.

BELLOWS SEALED FIRING PIN BACKGROUND OF THE INVENTION l Field of the Invention This invention relates to guns for firing caseless cartridges and particularly to a firing pin assembly adapted to seal the face of the breech block against the passage of the combustion gases produced by the firing of the cartridge.

2. Background of the Invention The use of caseless ammunition in a gun system offers several distinct advantages over conventional, cased ammunition. The primary advantages are a 30 percent to 40 percent reduction in weight and volume. Obviously, this volume and weight savings permits combat vehicles of all types to either carry significantly more ammunition or other stores, or to increase their combat radiuslln addition to these primary advantages, caseless ammunition eliminates the need for critical metal for the cases, and results in lower production costs. Finally, the extraction, control and disposal or storage of spent cases adds to the complexity of many systems, and this is eliminated by caseless ammunition.

A problem arises the use of caseless ammunition in precluding the passage of the combustion gases produced by the firing of the cartridge to the firing pin and its passageway through the bolt. These gases can otherwise produce major erosion of the bolt assembly. In cased ammunition, this function is provided by the case which expands within the chamber to seal the chamber from the breech block.

SUMMARY OF THE INVENTION Accordingly, it is an object of this invention to provide a sealed firing pin-bolt assembly.

It is a further object to provide such an assembly which may be made to have any desired stroke or penetration into the primer.

A feature of this invention is the provision of a firing pinbolt assembly including a tubular bellows having one end sealed to and about the penetrator end and its other end sealed to the bolt about the firing pin passageway.

BRIEF DESCRIPTION OF THE DRAWING These and other objects, features and advantages of the invention will be apparent from the following specification thereof taken in conjunction with the accompanying drawing in which:

FIG. 1 is a longitudinal cross section of a first embodiment of the invention; and

FIG. 2 is a longitudinal cross section of a second embodiment of this invention.

DESCRIPTION OF THE INVENTION The firing ,pin-bolt assembly may be incorporated in any conventional firearm having a bolt, but preferably, in the bolt of a firearm firing caseless ammunition.

The forward part of the bolt 10, shown in FIG. 1, has a stepped bore 12 including, seriatim, a forward longitudinal threaded portion 14, a longitudinal portion 16, a transverse face 18, and an aft longitudinal portion 20. A retaining bushing 22 is threaded into the bore portion 14 and has a stepped bore 24 which is coaxial with the bore 12, including a forward longitudinal portion 26, a transverse face 28, and a longitudinal portion 30. A mounting flange 32 has a central tubular body 34 with a bore 36 and an annular shoulder 38. The shoulder is captured between the bolt face 18 and the bushing portion 30. An annular groove 40 is formed into the face 18 and a static seal 42 is disposed therein. A firing pin 44 includes an aft rod portion 46, a two-step piston 48, 50, and a forward penetrator 52. A bellows 54 disposed about the rod portion 46 is advantageously formed of a plurality of flat stacked annular discs and has its forward end sealed to the aft face of the larger ,piston 48 and its aft end sealed to the forward face of the mounting flange 38. It will be seen that a continuous envelope is provided about the firing pin rod portion 46 and the passageway at and aft of the mounting flange by the two-stage piston 48, 50, the bellows 54, the mounting flange 38 and the static seal 42.

Firing is initiated by a blow applied to the aft, left end of the firing pin and takes place with the firing pin translated fully forward to the right, with the forward face 56 of piston 48 abutting the aft face 28 of the forward bushing portion 26. The gas pressure pulse generated in the chamber acts immediately on the forward face 58 of the piston 48 and begins to move the firing pin aft, to the left, closing the bellows rapidly.

To ensure that the bellows closes longitudinally without distorting transversely, the clearances between the peripheral surface of the piston portion 50 and the annular surface of the bore portion 26, and between the peripheral surface of the piston portion 48 and the bore portion 30, may be minimized. This will slow the flow of gas into the volume encircling the bellows, and ensure substantial closure of the bellows before significant lateral pressure develops. Once the bellows is longitudinally closed, the stacked discs forming the bellows serve as a thick walled tube which has a high resistance to transverse deformation.

A second embodiment of this invention is shown in FIG. 2 which further precludes transverse distortion of the bellows by trapping hydraulic fluid within the bellows during the interval of the gas pressure pulse.

The forward part of the bolt has a stepped bore 110, including, seriatim, a forward, longitudinal threaded portion 112, a longitudinal portion 114, a transverse face and an aft longitudinal portion 116. A retaining bushing 118 is threaded into the bore portion 112 and has a bore 120 which is coaxial with the bore 110. A mounting flange 122 has a central cone-shaped bore 124 therein, and is captured between the face 115 and the retaining bushing. An annular groove 126 is formed into the face 115 and a static seal 128 is disposed therein.

A firing pin 130 includes an aft rod portion 132, an aft cap portion 134 and a spring guide portion 135, a spring guide portion 136, a forward piston portion 138, and a forward penetrator 140. A check plate 142 having a bore 144 is disposed on the portion 132 between the mounting flange 122 and the spring guide portion 136. A check plate seating spring 143 is disposed on the rod portion 132 and the spring guide portion 136 between the check plate 142 and the forward piston portion 138. A stacked disc bellows 146 is disposed over the check plate and the spring, and has its aft end sealed to the mounting flange and its forward end sealed to the piston portion 138, between the forward piston portion 138 and the mounting flange. A stacked disc bellows 148 is disposed over the spring 150 and has its aft end sealed to the aft cap portion 134 and its forward end sealed to the mounting flange. The volume enclosed between the firing end cap, the piston, the two bellows and the mounting flange is filled with a hydraulic fluid.

Firing is initiated by a blow applied to the aft end of the firing pin, which drives the pin forwardly, to the right, so that the penetrator enters the primer in the chamber. As the pin moves to the right, the check plate is lifted from the mounting flanged to expose a generous passageway for the transfer of fluid from the aft, low-pressure bellows volume to the forward, high-pressure bellows volume. As soon as the fluid flow stops, the plate-seating spring reseats the check plate against the mounting flange. After the primer fires, gas pressure on the chamber builds up rapidly to a high level, e.g., 50,000 to 60,000 pounds per square inch. Ordinary bellows, if left unsupported cannot withstand such pressure. The purpose of the fluid is to provide internal support for the bellows during the brief period of maximum pressure. The fluid is substantially trapped in the forward volume by the reset check plate. However, a small annular passageway is provided between the rod portion and the check plate bore, so that fluid can escape slowly into the low-pressure volume to allow the firing pin to reset for the next shot under the combined action of decaying pressure and the pin-retracting spring, but so slowly as to provide a resisting support to the bellows during the gas pressure ulse.

p We claim:

1. A firing pin-bolt assembly comprising:

a bolt having a bore therein;

a firing pin disposed for reciprocation within said bore;

a bellows disposed around said firing pin and within said bore,

one end of said bellows being sealed to and around said firing pin,

the other end of said bellows being sealed to and around the peripheral surface of said bore.

2. An assembly according to claim 1 wherein the forward end of said bellows is sealed relatively adjacent the forward end of said firing pin and the aft end of said bellows is sealed relatively remote from the forward end of said bolt, whereby retraction of said firing pin results in contraction of said bellows.

3. An assembly according to claim 2 wherein said forward end of said firing pin includes a piston having a primer penetrator extending therefrom.

4. An assembly according to claim 3 further including means for limiting the extent of the forward and the aft reciprocation of said firing pin.

5. An assembly according to claim 3 wherein said piston has a relatively small clearance within said bore, whereby substantially all gas pressure is developed on the forward face of said piston, and substantially little gas pressure is developed behind said piston.

6. An assembly according to claim 2 wherein said bellows is formed of a plurality of stacked discs.

7. An assembly according to claim 1 further including:

an additional bellows disposed around said firing pin;

one end of said additional bellows being sealed to and around said firing pin,

the other end of said bellows being sealed around the peripheral surface of said bore;

a hydraulic check valve disposed between said bellows and obturating said bore therebetween; and

a hydraulic fluid disposed within the open volume defined by and between said bellows.

8. An assembly according to claim 7 wherein:

the forward end of said first mentioned bellows is sealed relatively adjacent the forward end of said firing pin, and the aft end of said bellows is sealed relatively remote from the forward end of said bolt;

the aft end of said additional bellows is sealed relatively adjacent the aft end of said firing pin, and the forward end of said additional bellows is sealed relatively remote from the aft end of said bolt;

whereby retraction of said firing pin results in contraction of said first-mentioned bellows and extension of said additional bellows.

9. An assembly according to claim 8 wherein said forward end of said firing pin includes a piston having a primer penetrator extending therefrom.

10. An assembly according to claim 7 further including spring means for biasing said firing pin aft.

11. An assembly according to claim 8 wherein said check valve permits a high rate of hydraulic flow forwardly and a low rate of flow aft.

12. An assembly according to claim 9 wherein each of said bellows is formed of a plurality of stacked discs. 

1. A firing pin-bolt assembly comprising: a bolt having a bore therein; a firing pin disposed for reciprocation within said bore; a bellows disposed around said firing pin and within said bore, one end of said bellows being sealed to and around said firing pin, the other end of said bellows being sealed to and around the peripheral surface of said bore.
 2. An assembly according to claim 1 wherein the forward end of said bellows is sealed relatively adjacent the forward end of said firing pin and the aft end of said bellows is sealed relatively remote from the forward end of said bolt, whereby retraction of said firing pin results in contraction of said bellows.
 3. An assembly according to claim 2 wherein said forward end of said firing pin includes a piston having a primer penetrator extending therefrom.
 4. An assembly according to claim 3 further including means for limiting the extent of the forward and the aft reciprocation of said firing pin.
 5. An assembly according to claim 3 wherein said piston has a relatively small clearance within said bore, whereby substantially all gas pressure is developed on the forward face of said piston, and substantially little gas pressure is developed behind said piston.
 6. An assembly according to claim 2 wherein said bellows is formed of a plurality of stacked discs.
 7. An assembly according to claim 1 further including: an additional bellows disposed around said firing pin; one end of said additional bellows being sealed to and around said firing pin, the other end of said bellows being sealed around the peripheral surface of said bore; a hydraulic check valve disposed between said bellows and obturating said bore therebetween; and a hydraulic fluid disposed within the open volume defined by and between said bellows.
 8. An assembly according to claim 7 wherein: the forward end of said first mentioned bellows is sealed relatively adjacent the forward end of said firing pin, and the aft end of said bellows is sealed relatively remote from the forward end of said bolt; the aft end of said additional bellows is sealed relatively adjacent the aft end of said firing pin, and the forward end of said additional bellows is sealed relatively remote from the aft end of said bolt; whereby retraction of said firing pin results in contraction of said first-mentioned bellows and extension of said additional bellows.
 9. An assembly according to claim 8 wherein said forward end of said firing pin includes a piston having a primer penetrator extending therefrom.
 10. An assembly according to claim 7 further including spring means for biasing said firing pin aft.
 11. An assembly according to claim 8 wherein said check valve permits a high rate of hydraulic flow forwardly and a low rate of flow aft.
 12. An assembly according to claim 9 wherein each of said bellows is formed of a plurality of stacked discs. 